Method of extrusion with liquidpressure and means for carrying out the method



Sept. 15, 1970 J, ss0 3,528,269

METHOD OF EXTRUSION WITHLIQUID-PRESSURE AND MEANS FOR CARRYING OUT THE METHOD Filed Feb. 29, 1968 4 I 1% m P; 6/ 4'7 1 t: A #2193 j \\1 l Fig.4

I MW] INVENTOR. JAN N/LSSO/V United States Patent O Int. (:11 B21c 23/08 US. CI. 72-60 Claims ABSTRACT OF THE DISCLOSURE A pressure cylinder having a bore therethrough is arranged horizontally within a collapsible open-topped container for liquid. At one end of this container is arranged a rod having a central opening therethrough, the end of which fits into the bore of the cylinder, and carries a die. The other end of the container is connected to a hydraulic pressure piston which has a projecting plunger engaging in the other end of the bore in the pressure cylinder, with a spring on the end of this rod supporting a pressure member. A billet is inserted into the bore and is pressed by the hydraulic pressure piston until the carrier for the rod connected to this piston engages the cylinder, whereupon the cylinder is caused to move along with the rod over the rod connected to the fixed end, so as to express the billet completely.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a method of rod extrusion with fluid-pressure and means for carrying out the method.

The prior art It is known that a high hydrostatic pressure increases the plasticity of an otherwise relatively brittle material. It is also known to exploit this phenomenon in rod extrusion by using fluid as pressure-transmitting medium. The method can be characterised as a form of cold rod extru sion. However, the punch does not operate directly on the billet as with conventional rod extrusion but instead on a fluid volume enclosed in a pressure cylinder. The billet is thus subjected to hydrostatic pressure all over except for the side which closes the nozzle. If the pressure is sufiiciently increased the material will be extruded. Products which can be manufactured in this way are rods, sections, tubes, wire, etc.

With conventional means for carrying out rod extrusion with fluid-pressure the die is arranged at one end of the hollow space in a pressure cylinder while the billet-and afterwards the punch-is inserted at the other end. In order to achieve as high a production rate as possible it is desirable to use as great a volume of the billet as possible. The diameter of the billet is limited to a certain maximum value which is determined by the size of the rod cross section, fluid-pressure available and the material properties of the billet and which may not be exceeded if the billet material is to be extruded through the nozzle. Neither can the length of the billet be greater than the length of the punch, which length for reasons of strength must be limited to a certain maximum value determined by the diameter of the punch and the pressure used. If one endeavours to increase the rigidity of the punch by giving it a diameter which is considerably greater than the diameter of the billet, this will cause a corresponding increase in the pressure required and at the 'ice same time an increase in the volume of the liquid in the pressure chamber so that the suspension in the system is greater which is a disadvantage.

SUMMARY OF THE INVENTION With a method according to the invention it is possible with a certain available pressure and a certain rod section to use a billet volume which is considerably greater than the corresponding volume with conventional methods for rod extrusion with fluid-pressure.

A method according to the invention is characterised in that a part of the billet is pressed through the die with the help of a first punch inserted at one end of the pressure cylinder, while said pressure cylinder is held in its initial position by a pull-back device, and the die is arranged at the other end of the pressure cylinder and mechanically connected to a stationary second punch provided with a central channel, after which said pressure cylinder, by means of a stopping disc on the punch-holder of the first punch, is pressed towards said second punch, after which the pressure piston and pressure cylinder are removed from the die and said second punch by means of said pull-back device, and a fresh billet is inserted in the die, after which the pressure cylinder and said first punch are returned to their initial positions and the cylinder space thus produced is supplied with the required quantity of fluid pressure medium.

The invention also relates to a means for carrying out the above-mentioned method, which means comprises a first punch connected to the pressure piston in a high pressure press and insertable into one end of the pressure cylinder, a container for pressure medium which can communicate with the pressure cylinder, a die to be suspended in the pressure cylinder and a pull-back means for axial movement of the pressure cylinder, characterised in that the device also comprises a second punch insertable at the other end of the pressure cylinder, said first punch is at its attachment end being furnished with a stopping surface facing an end surface of the pressure cylinder, and said second punch being rigidly arranged in relation to a fixed table, provided with a central channel for the extruded rod and mechanically connected to said die.

By using two punches according to the invention instead of oneas in known methodsit is possible to use a billet which is approximately twice as long as a corresponding billet in conventional methods, which is thus equivalent to approximately double the billet volume. There is thus a completely continuous transition from the relative movement between the pressure cylinder and one of the punches and a relative movement between the pressure cylinder and the other punch.

BRIEF DESCRIPTION OF THE DRAWINGS DESORIPTION OF THE PREFERRED EMBODIMENTS In the drawings 1 designates the pressure piston of a hydraulic press having horizontal pressing directions and 2 the stationary table which is arranged with the surface in a vertical plane. The device comprises a movable punch 3 and a stationary punch 4. The stamp 3 is attached to the piston 1 by means of a clamping device 5 and the punch 4 to the fixed table 2. The punches 3 and 4 are arranged to have by their active ends inserted into the respective ends of the pressure cylinder 6 which has a pressure chamber 7 in the form of a through-running axial bore. The pressure cylinder 6 is displaceable in axial direction and can be set in the desired position by means of pull-back cylinders 8 in the fixed table and pistons, not shown in the figures. The mechanical connection between the pistons of the operating cylinders and the pressure cylinder is effected by rods 9. The die 10 is rigidly connected to the stationary punch 4 which is provided with a central channel 11 for the extruded rod, which also runs through a corresponding channel 12 in the fixed table. The pressure punch 3 is provided with a stopping disc 17 which abuts the end of the pressure cylinder when the punch is fully inserted. A spring 13 is attached by one end to the active end of the punch 3 and by its other end to a Washer 14 which has sufficient clearance in relation to the inner walls of the pressure cylinder for pressure medium to be able to flow in the gap. The pressure cylinder 6 and the punches 3 and 4 are immersed in a bellows-like container 15 for pressure medium, which is flexible in horizontal direction and clamped by one end in the fixed table 2 and by the other end to the punch-holder 5. The pressure medium 16 has a surface level which is higher than the upper edge of punches and the container 15 is open at the top so that the billet 16 can easily be placed in the tool.

The working cycle is as follows:

FIG. l.-The billet 16 is held by the spring 13 against the die 10 so that the fluid pressure does not influence the billet surface abutting the die. The movable punch 3 is pressed into the pressure chamber 7 in the pressure cylinder 6 and the billet starts to be forced out through the die 10.

FIG. 2.The punch 3 is pressed with its entire active length into the pressure cylinder 6 and the pressure transfer between the piston 1 and the pressure cylinder 6 takes place through the stopping disc 17, whereupon the pressure cylinder 6 is set in movement in relation to the stationary punch 4 which is then pressed into the pressure chamber 7.

FIG. 3.--Pressing is completed.

FIG. 4.-The pressure cylinder 6 and piston 1 are returned by the pull-back cylinders 8 to the position shown in FIG. 4. The extruded rod is cut and the die 10 is rinsed or replaced by a new die. New billet is inserted and held between the pressure cylinder 6 and the die 10.

FIG. 5.The pressure piston is set in movement towards the stationary punch 2 so that the billet is clamped against the die by the spring 13 and the punch 3 is pressed out of the pressure cylinder so that the pressure cylinder and punch finally take up the same position as in FIG. 1.

I claim:

1. A method of rod extrusion with fluid pressure by means of a mechanism which includes a pressure cylinder with a longitudinal bore arranged between a table and a pressure piston, a pull-back device, a hollow punch mounted on said table, a solid punch connected to said piston and having a stop surface at its base, and a die,

4 slidable in said bore, supported by said hollow punch, which method comprises the steps of inserting an extrusion billet with its full length into said bore, supplying pressure liquid to said bore, inserting the punch-supported die at one of the bore ends and the solid punch at the other end of the bore, thereby closing the bore, moving said pressure piston towards said table until the whole insertable length of said solid punch is inserted in the bore and said stopping surface brought into engagement With an end of the pressure cylinder, thereby extruding part of the billet, and continuing the movement of the pressure piston so as to move said pressure cylinder towards said table, 'whereby the remaining part of the billet is extruded by a movement of the die and the hollow punch along the bore.

2. Device for rod extrusion with fluid pressure, comprising a high pressure press with a pressure piston, a fixed table, a pressure cylinder with an axial bore, a die, a hollow punch, a solid punch, a pull-back means, stopping means for said solid punch, first punch fastening means for rigidly attaching said hollow punch to said table, second punch fastening means for rigidly attaching said solid punch to said pressure piston, said pull-back means including means movably supporting said pressure cylinder between said table and pressure piston, the center line of said bore coinciding .with the center line of said punches, said punches and said die being slidable in said bore, means rigidly attaching said die to said hollow punch, said stopping means including means to stop relative movement between said pressure cylinder and said solid punch at an intermediate extrusion stage and simultaneously establish a, force transferring connection between the pressure cylinder and the pressure piston, the pressure cylinder being movable under influence of the force transmitted, and the die being moved into said bore beginning at said intermediate extrusion stage.

3. Device according to claim 2, in which said punches have a substantially horizontal pressing direction and said second punch (4), together with at least a part of said pressure cylinder, is arranged in an open container (15) for pressure fluid, wherein the fluid level is higher than the highest point in the interior of the pressure cylinder 4. Device according to claim 3, in which the container for pressure fluid is adjustable in length in the pressing direction.

5. Device according to claim 2, in which a spring compressible in the pressing direction is attached by one end to the end surface of said first punch.

References Cited UNITED STATES PATENTS 3,364,716 l/196 8 Averill et al. 72-60 3,390,563' 7/1968 Fuchs 7260 3,434,320 3/1969 Green 7260 RICHARD J. HERBST, Primary Examiner U.S. Cl. X.R. 72270 

